It is conventional to apply membranes to roofs in order to prevent the entry of moisture into the structure of which the roof forms a part. These membranes are made of a synthetic, rubber-like material which is flaccid and waterproof and typically are 3/64" thick; they are supplied in rolls of 100' length and vary in width from 4'6" to 45'.
There have been four systems utilized for fastening the membranes. In the adhered system, a suitable cement is applied to the substructure surface and the rubber-like membrane applied over it; there is an overlap of one membrane sheet with the next, so as to provide a water impervious lap joint. A partially adhered method or system is used, wherein the bonding of the membrane takes place at special plate areas or locations. The ballasted system involves the holding down of the membrane with a layer of small stones. There is also used a mechanically fastened system, in which battens or other strips are placed on the membrane and are adhered, with complex systems for connecting the batten and sealing it. The batten is a strip of rubber or plastic material and is utilized in order not only to hold the sheet down against wind forces which might tend to lift it (as do the other systems) but also prevents or retards creeping movement of the sheet due to expansion and contraction. The seal utilized with the batten strip is a small membrane sheet which entirely covers the batten strip and which is glued down over the entire strip. All of the foregoing systems suffered either from expense of installation, or expense of materials, or both.